1. Field of the Invention
The present invention relates to imaging apparatus, more particularly, to a manner of dealing with control data in signal processing performed in a reproducing apparatus or a recording apparatus.
2. Description of the Related Art
Various types of apparatus are known for recording and reproducing pictures in which the image signals of objects are produced by a solid-state image sensor such as a CCD, then after signal-processing, these image signals are recorded on a recording medium such as a magnetic tape and a magnetic disk. As an example, an electronic still camera records an object image on a recording medium as a still image. Control of white balance (hereafter referred to as WB) for color image signals obtained by taking the picture is an example of signal processing performed on the image signals depending on the data representing the condition under which a picture is taken.
Two known technologies for automatically performing WB control are an external WB method and an internal WB method called a TTL (Through the Lens) method.
In the external WB method, for example, the ratio of the red (R) component to the blue (B) component is determined for the light passing through the filters disposed on a front surface of a camera and the resulting ratio is used as WB data. In the TTL method, on the other hand, a picture of a reference object is taken before taking a picture of an actual object and the image signal of the reference object is used to performed WB control.
Comparing these two methods of WB control, the TTL method is generally more advantageous than the external WB method with regard to the size and cost of apparatus. In either case, WB control is carried out on the image signal obtained by taking a picture, and then the image is recorded on a recording medium as image color signals which are controlled in gain to a desired value.
One possible arrangement is to record the data for use in signal processing such as WB control on a recording medium together with normal image signals obtained by taking a picture. This arrangement is useful to reduce the requirement of memory capacity of the apparatus and to reduce the processing time required for taking a picture, because the WB control may be performed when the picture is reproduced.
However, in the case of such an electronic still camera in which the control data is recorded on a recording medium, if the recording medium is detached from the camera, the WB control data becomes not available, and thus it becomes impossible to perform WB control.
Furthermore, the WB control data associated with even the same reference object will be different depending on the season and the time when the WB data is produced, and also depending on the location where the WB data is produced. As a result, it is very difficult to make proper utilization of the WB control data which is recorded on the recording medium.
On the other hand, while the TTL method has generally an advantage in the size and cost over the external WB method, in some cases it is impossible to perform as accurate control as required. For example, when the object has a large magnitude of vivid color components, the gain control of the color signals is performed such that the vivid color components are suppressed, and thus the reproduction from image signals obtained by taking a picture lacks vividness in colors.